Week 3 - Genetics and Evolution

Behavioral Genetics

Study of how genes and environments influence behaviour

Adoption Study

compare adopted children to adoptive & biological parents

Twin Studies

compare similarity of identical and fraternal twins

Monozygotic Twins

identical

Dizygotic Twins

fraternal

Quantitative Genetics

Discipline of study: similarities between on individuals based on biological relation

Heritability Coefficient (0-1)

single measure of genetics' influence on a trait, difficult to interpret

Behaviorism

Behavior comes from environmental factors

Psychoanalysis

Roots of behavior comes from early life-histories

Can you organize traits from more to less genetic?

no

Gene-environment interaction

genetic differences affect only behavior under some environmental circumstances

Epigenetics

Changes in gene expression because of environment, can be passed on

DNA methylation

decreases transcription, adding methyl groups

Acetylation (histone modification)

increase transcription, changes charge and uncoils DNA

Why difficult know nurture or nature?

Genetics and environment = interconnected, genetic impact is spread over many genes, rare to see extreme hardship effecting behavior

Intrasexual Competition

competition between members of 1 sex -> winner gets to mate

Intersexual Selection

members of 1 sex attracted to certain quality -> passed on

Gene Selection Theory

Ways Genes boost replicative success: 1) influence odds of survival & reproduction 2) help other organisms with same genes

Psychological Adaptations

mechanisms of mind evolved to solve specific survival/reproduction problems

Physiological Adaptations

Adaptations in body because of environment (input, procedure, output)

What type of framework is evolutionary psychology?

Interactionist

What is an interactionist framework?

theory: takes into account multiple factors when determining outcome

What has a big effect on psychological adaptations? (evolutionary psychology)

culture

Sexual Strategies Theory

humans evolve diff mating strategies (long & short-term), vary depending on culture, social context, parental influence, personal mate value

Initial focus of sexual strategies theory

differences between men and women in mating preferences and strategies

Error Management Theory

When have uncertain situation with a safer vs dangerous choice, will choose choose choice with lower cost of errors

Cost Asymmetric

cost vs rewards

Visual Descent Illusion

height looks higher when look down vs looking up

Auditory Looming Bias

Object sound when moving towards rather than moving away

Sexual Over perception Bias

Men over read into sexual interest

Phenotypic plasticity

different morphology, physiology, behavioral outcome from a single genome in response to changes in environment

Epigenetics

transmission of phenotype w/out changes in DNA sequence

Epigenome

genome-wise distribution of epigenetic marks

DNA methylation

adding methyl group to cytosine

Effects of DNA methylation

gene silencing, reduced gene expression

Histone Acetylation

gene activation, increased gene expression, associated w/demethylation

Histone Deacetylation

Gene silencing, decreased gene expression, associated w/ DNA methylation

Opposing enzymes involved in de/acetylation

Histone Acetyltransferases (HATs) & Histone Deacetylases (HDACs)

Histone Code

Determines cell specific gene expression programs

Environment adjusts pathways in children that support...

Biological defensive systems for survival, reproductive success, adequate parenting next generation

Effect of better childhood...

higher expression glucocorticoid receptor in hippocampus = lower hormonal response to stress

Effect of worse childhood...

lower histone acetylation = DNA methylation = lower glucocorticoid receptors = higher hormonal response to stress

How does nutrients reverse/change DNA methylation & histone modification?

inhibit enzymes that catalyze DNA methylation/histone modification, alter substrate availability needed for enzyme rxn

DNA methylation effect on memories

maintain long-term memories, effect synaptic plasticity & cognitive function, psychological illnesses

Effect of Increased Histone Acetylation on Memory?

memory formation, increased synaptic tranmission

Effect of increased histone de-acetylation of memory?

reduced synaptic plasticity, impaired memory

Rett Syndrome

mutation in MECP2: disrupted regulation of histone modification & gene expression -> increased anxiety, cognitive deficits, social withdrawal

Rubinstein-Taybi Syndrome

Mutation in CBP gene: decreased histone acetylation = cognitive dysfunction (learning and memory)

Role of MECP2 gene

read DNA sequence to check for DNA methylation & bind, promote necessary proteins, ensure DNA packaged properly, assist production of proteins

CBP genes

bind to specific histone = promote histone acetylation = promote gene expression

What are DNA methylation alterations associated with?

mental illness

Epigenetics of depression

Altered chromatin structure -> regulate programs of gene expression, down regulated levels of histone markets for increased gene expression

Epigenetics in Suicide

reduced gene expression = reduced learning and memory

What can moderate effects of childhood adversity on mental illness?

Genes like glucocorticoid receptor